Category and Location Groups

Is it possible to have Category and location groups, similar to the grouping system for calendars.

For example, say I have a range of suppliers and I have a calendar for expenses, I could have the name of each supplier setup as a category. All of these categories could then be grouped under one group say expense's.

Then If there could be some way of limiting the group of Categories available to that particular calendar, when an event is created. Maybe under Calendar properties/event defaults it would save scrolling through a long list.

The same could apply to locations. resticting certain locations to specific Calendars

Long after this suggestion was posted, I discovered it when I set up different calendars. It seems that categories, locations, priorities are common to all categories. It would be nice to have separate categories, locations, etc. for each different calendar. It would make it more specific and less cluttered.